Changes in the localized surface plasmon resonance (LSPR) of gold nanorods (AuNRs) due to halide anion adsorption were probed by dark-field scattering through a spectroelectrochemical flow cell. The LSPR of the same AuNR on an indium tin oxide electrode was measured in NaF, NaCl, and NaBr to directly compare the effect of halide ion adsorption, which was tracked by changes in plasmon resonance energy, linewidth, and peak intensity extracted from a Lorentzian fit to single AuNR scattering spectra. We demonstrate that at weak electrode potentials, the change in LSPR is anion independent, indicating charge density tuning and physisorption of anions. At intermediate and strong potentials, the magnitude of the change in the LSPR follows anion reactivity due to local refractive index changes and chemical interface damping caused by anion chemisorption. The peak scattering intensity of the AuNRs decreases with each potential cycle at strong potentials and high electrolyte concentration. The decrease in intensity indicates AuNR dissolution, and particle reshaping due to the dissolution is tracked by irreversible changes in the plasmon resonance energy and linewidth with each cycle.

Spectroelectrochemistry of halide anion adsorption and dissolution of single gold nanorods

251st National Meeting (2016)

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